I'm pretty sure the guy you quoted is full of it, and I've included the quotes that I don't think he could back up with evidence. I've found at least two sources that would appear to directly contradict the bold part above.Global warming debunked....
Man's contribution to the greenhouse gases was so small we couldn't change the climate if we tried, he maintained...
Water vapour was responsible for 95 per cent of the greenhouse effect...
The other greenhouse gases: carbon dioxide, methane, nitrogen dioxide, and various others including CFCs, contributed only five per cent of the effect, carbon dioxide being by far the greatest contributor at 3.6 per cent.
However, carbon dioxide as a result of man's activities was only 3.2 per cent of that, hence only 0.12 per cent of the greenhouse gases in total. Human-related methane, nitrogen dioxide and CFCs etc made similarly minuscule contributions to the effect: 0.066, 0.047 and 0.046 per cent respectively...
This one also offers a good explanation of how we know that the rising carbon levels are due to human activity. The contributors to the cite also appear to be climate scientists.
RealClimate » How do we know that recent CO2 increases are due to human activities?
The following is from a BBC article discussing a 2004 study of ice cores.Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). The fact that this is due virtually entirely to human activities is so well established that one rarely sees it questioned.
BBC NEWS | Science/Nature | CO2 'highest for 650,000 years'
"We find that CO2 is about 30% higher than at any time, and methane 130% higher than at any time; and the rates of increase are absolutely exceptional: for CO2, 200 times faster than at any time in the last 650,000 years."